[kubeadm] use v1beta3 configuration version

* extra admission controls now don't have a version in their file names
  eventratelimit.v1beta2.yaml.j2 -> eventratelimit.yaml.j2
* cri_socket variable includes the unix:// prefix to be conformat with
  upstream

roles/kubernetes/control-plane/templates/admission-controls.yaml.j2

@@ -0,0 +1,9 @@
+apiVersion: apiserver.config.k8s.io/v1
+kind: AdmissionConfiguration
+plugins:
+{% for plugin in kube_apiserver_enable_admission_plugins[0].split(',') %}
+{% if plugin in kube_apiserver_admission_plugins_needs_configuration %}
+- name: {{ plugin }}
+  path: {{ kube_config_dir }}/{{ plugin|lower }}.yaml
+{% endif %}
+{% endfor %}